// 单行注释
/* 多行注释*/
/* 外部JS文件 */
document.querySelectorAll('.btn').forEach(
  btn =>
    (btn.onclick = function () {
      let now = new Date()
      let year = now.getFullYear()
      let month = now.getMonth() + 1
      let day = now.getDate()
      alert(year + '/' + month + '/' + day)
    })
)
